Scalable 2.45 GHz electrically small antenna design for metaresonator array

Abstract

In many planar antenna array designs, impedance transformers are required to interconnect the elements to ensure that their impedances are matched. However, impedance transformers take up space and reduce area utilisation. If each element is electrically small and able to function individually as an electrically small antenna (ESA), they can be combined into an array without using impedance transformers. In this study, a stubbed hexagonal shaped folded dipole ESA of one tenth of the wavelength is proposed and developed. This metamaterial inspired design of loading the folded dipole with split ring resonator overcomes the problem of fabricating ESA of one tenth of the wavelength using typical printed circuit board fabrication technologies for the 2.45 GHz band. To show the potential of using this ESA as a unit element for antenna array without using impedance transformers, a seven-element array is designed and fabricated. By optimising the element separation distance, and stub lengths, the ESA array shows good S(11) of less than −25 dB, and gain improvement of up to 12 dB compared with a single unit ESA.

Keywords

• planar antenna arrays
• UHF resonators
• metamaterial antennas
• dipole antenna arrays
• impedance matching
• impedance convertors
• scalable electrically small antenna design
• metaresonator array
• impedance transformer
• planar antenna array design
• impedance matching
• stubbed hexagonal shaped folded dipole ESA
• split ring resonator
• printed circuit board fabrication technology
• seven-element array fabrication
• frequency 2.45 GHz